| Paper | Title | Page |
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| WEBX01 | Recent Development of the IMPACT Parallel Beam Dynamics Code Suite | 0 |
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| In this paper, we report on recent development of new capabilities to the IMPACT parallel beam dynamics code suite. These new capabilities include modeling multiple charge state beam, modeling ion beam formation and transport in LEBT, horizontal/vertical bend, higher order multipoles, rf traveling wave structure and wake fields. We will present physical models and computational methods for these new capabilities. Some application examples will also be presented in this paper. | ||
| WEBX02 | Observation of Emittance Growth at the injection in the KEK PS Main Ring | 250 |
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| We have been studying the emittance growth and beam loss mechanism during the injection period of the 12 GeV main ring of the KEK proton synchrotron to achieve higher intensity. The typical beam loss is about 30 % during the injection period of 500 milliseconds for the high intensity operation. Measurement of the transverse beam profiles using flying wires has revealed a characteristic temporal change of the beam profile within a few milliseconds after the injection. Horizontal emittance growth was observed when the horizontal tune was close to the integer. The effect was more enhanced for higher beam intensity and could not be explained with the injection mismatch. A resonance created by the space charge field was the cause of the emittance growth. A multiparticle tracking simulation program, ACCSIM, taking account of space charge effects has successfully reproduced the beam profiles. | ||
| WEBX03 | Modeling of Non-linear Effects in RF Cavities | 0 |
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Emerging accelerator applications require electron beam radii comparable to RF cavity apertures, placing more stringent demands on the modeling of particle motion in RF cavities using map-based techniques. High-gradient cavities and cavities with significant axial asymmetries also demand improvements in modeling capabilities. A new method has been developed for computing high-order nonlinear maps for arbitrary RF cavities*. It has been implemented through fifth order in MaryLie/IMPACT, so simulations can include the effects of space-charge. We describe this new approach and present comparisons with more traditional approaches.
* D. T. Abell, submitted to PRST-AB. |
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| WEBX04 | Measurement strategy for the CERN Linac4 Chopper-line | 262 |
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| Linac4 is a new accelerator under study at CERN. It is designed to accelerate H- ions to 160 MeV of energy, for injection into the existing Proton Synchrotron Booster. The low energy section, comprising an H- ion source, a 352 MHz Radio Frequency Quadrupole and a 3 MeV chopper line will be assembled at CERN in the next years. Linac 4 is also designed as an injector for the SPL, a high power proton driver delivering 5MW at 3.5 GeV. In this case the beam losses must be limited to 1 W/m and therefore the formation of transverse and longitudinal halo at low energy becomes a critical issue which has to be measured and controlled. The chopper-line is composed of 11 quadrupoles, 3 bunchers and the chopper itself. Its beam dynamics will be characterized with specific detectors and diagnostic lines. In particular the transverse and longitudinal halo will be measured by a Beam Shape and Halo Monitor (BSHM) with a sensitivity of 10.000 particles per bunch and a time resolution of 2ns. In this paper we present the simulation work in preparation for the measurement campaign scheduled in 2008. | ||
| WEBX05 | Scaling laws for space charge resonances | 268 |
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| Space charge can be the driving term of nonlinear resonances, like the resonant emittance exchange 2Qx-2Qy=0 ("Montague resonance", in linacs and high-intensity rings), or the fourth-order structure resonance 4Qx=n (high-intensity rings, FFAG's). In this study we present scaling laws to describe the dependence of the expected emittance growth effect on the initial emittances, the tune shift and/or the crossing rate through the resonance. | ||
| WEBX06 | Analysis of emittance growth in the Fermilab Booster | 271 |
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| Multi-particle similations are performed to study emittance growth in the Fermilab Booster. Analysis shows that the sourcce of the vertical emittance growth comes mostly from random errors in skew quadrupoles as well as the transverse space-charge force. Random errors in the dipole fields and the Montague resonance do contribute but to a much lesser extent. The effect of random errors in the quadrupoles is small because the betatron envelope tunes are resonably far away from the half-integer stopband. |